<!doctype html>
<html lang="en">
 <head>
  <meta charset="UTF-8">
  <meta name="Generator" content="EditPlus®">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <title>Document</title>
 </head>
 <body>
  
 </body>
</html>
<script>
	var a = '2';
	// '2' !== 2;
	switch(a){
		case 2: //连类型也要比较
			alert('相等');
			break;
		default:
			alert('都不相等');
			break;
	}
</script>
